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package org.apache.juneau.svl;

import static org.apache.juneau.internal.ClassUtils.*;

import java.util.*;

import org.apache.juneau.svl.vars.*;

/**
 * Builder class for building instances of {@link VarResolver}.
 * 
 * <h5 class='section'>See Also:</h5>
 * <ul>
 * 	<li class='link'><a class="doclink" href="../../../../overview-summary.html#juneau-svl.VarResolvers">Overview &gt; juneau-svl &gt; VarResolvers and VarResolverSessions</a>
 * </ul>
 */
public class VarResolverBuilder {

	private final List<Class<? extends Var>> vars = new ArrayList<>();
	private final Map<String,Object> contextObjects = new HashMap<>();

	/**
	 * Create a new var resolver using the settings in this builder.
	 * 
	 * @return A new var resolver.
	 */
	public VarResolver build() {
		return new VarResolver(vars.toArray(new Class[vars.size()]), contextObjects);
	}

	/**
	 * Register new variables with this resolver.
	 * 
	 * @param vars
	 * 	The variable resolver classes.
	 * 	These classes must subclass from {@link Var} and have no-arg constructors.
	 * @return This object (for method chaining).
	 */
	@SuppressWarnings("unchecked")
	public VarResolverBuilder vars(Class<?>...vars) {
		for (Class<?> v : vars) {
			newInstance(Var.class, v);
			this.vars.add((Class<? extends Var>)v);
		}
		return this;
	}

	/**
	 * Adds the default variables to this builder.
	 * 
	 * <p>
	 * The default variables are:
	 * <ul>
	 * 	<li>{@link SystemPropertiesVar}
	 * 	<li>{@link EnvVariablesVar}
	 * 	<li>{@link ArgsVar}
	 * 	<li>{@link ManifestFileVar}
	 * 	<li>{@link SwitchVar}
	 * 	<li>{@link IfVar}
	 * 	<li>{@link CoalesceVar}
	 * 	<li>{@link PatternMatchVar}
	 * 	<li>{@link UpperCaseVar}
	 * 	<li>{@link LowerCaseVar}
	 * 	<li>{@link NotEmptyVar}
	 * </ul>
	 * 
	 * @return This object (for method chaining).
	 */
	public VarResolverBuilder defaultVars() {
		return vars(
			SystemPropertiesVar.class, 
			EnvVariablesVar.class, 
			ManifestFileVar.class, 
			ArgsVar.class,
			SwitchVar.class, 
			IfVar.class, 
			CoalesceVar.class, 
			PatternMatchVar.class, 
			UpperCaseVar.class, 
			LowerCaseVar.class, 
			NotEmptyVar.class);
	}

	/**
	 * Associates a context object with this resolver.
	 * 
	 * <p>
	 * A context object is essentially some environmental object that doesn't change but is used by vars to customize
	 * output.
	 * 
	 * @param name The name of the context object.
	 * @param object The context object.
	 * @return This object (for method chaining).
	 */
	public VarResolverBuilder contextObject(String name, Object object) {
		contextObjects.put(name, object);
		return this;
	}

	/**
	 * Associates multiple context objects with this resolver.
	 * 
	 * <p>
	 * A context object is essentially some environmental object that doesn't change but is used by vars to customize
	 * output.
	 * 
	 * @param map A map of context objects keyed by their name.
	 * @return This object (for method chaining).
	 */
	public VarResolverBuilder contextObjects(Map<String,Object> map) {
		contextObjects.putAll(map);
		return this;
	}
}